Effect of the TI/TE ratio on mean intratracheal pressure in high-frequency oscillatory ventilation.

@article{Thome1998EffectOT,
  title={Effect of the TI/TE ratio on mean intratracheal pressure in high-frequency oscillatory ventilation.},
  author={Ulrich H. Thome and Frank Pohlandt},
  journal={Journal of applied physiology},
  year={1998},
  volume={84 5},
  pages={
          1520-7
        }
}
In high-frequency oscillatory ventilation (HFOV), an adequate mean airway pressure is crucial for successful ventilation and optimal gas exchange, but air trapping cannot be detected by the usual measurement at the y piece. Intratracheal pressures produced by the high-frequency oscillators HFV-Infantstar (IS), Babylog 8000 (BL), and the SensorMedics 3100A (SM) [the latter with either 30% (SM30) or 50% (SM50) inspiratory time] were investigated in four anesthetized tracheotomized female piglets… 
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In a neonatal piglet model of pneumothorax treated with HFOV, with amplitude adjusted to maintain constant alveolar ventilation, gas flow through the chest tube was significantly lower at 15 Hz compared with either 10 Hz or 5 Hz.
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Awareness of the different mechanisms governing gas transport and the prevailing lung mechanics during HFOV represents essential background for the physician planning to use this mode of ventilation in the adult patient.
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HFOV with a low oscillatory frequency may afford benefit in preterm babies with severe PIE, and 15 infants survived, including 10 of the bilateral cases (71%), and all of the unilateral cases.
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Clinicians should be aware that modern high-frequency oscillators exhibit important differences in the delivered ΔP and VT, with some unable to deliver VT >3 ml at 15 Hz, and others generating VT >20 ml at 5 Hz and a 1:1 inspiratory-to-expiratory time ratio.
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Oscillators with square waves or an inspiratory incisura exhibited the highest number of nonfundamental frequency components on power spectral density analysis, suggesting more complex harmonic waveforms with potentially greater transmissive power to the lungs.
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